Windshield wiper system especially for motor vehicles

ABSTRACT

This invention describes a so-called reciprocating wiper system having a guide housing moving pendulum fashion and a wiper arm guided therein and radially retractable and extractable, wherein by various measures the volume of the guide housing is changed as compared to known embodiments and thus adapted to the space conditions in the engine compartment of a motor vehicle, wherein because of a change in the volume a lengthening of the wiper blade and thus an enlargement of the wiping area is made possible.

This is a continuation of application Ser. No. 223,201, filed Apr. 20,1988, now abandoned.

This invention relates to a windshield wiper system according to thefeatures of the preamble of claim 1.

A windshield wiper system of this kind is known from the DE-OS No. 33 24634. The wiper arm-and-blade assembly of a windshield wiper system ofthis kind is, if required, several times retracted and extracted in theradial direction during its swivelling motion, so that also the cornerareas of the windshield are cleaned. The radial displacement of thewiper arm-and-blade assembly or of the piston connected with the formand displaceably mounted in a guide housing moving in pendulum fashionis in the known embodiment derived from the rotation of a shaftsupported on the guide housing, which shaft carries a pinion outside theguide housing, which pinion meshes with a stationarily arranged toothedsegment. The guide housing itself is driven via a shaft which is movableguided in a bearing bush of a supporting frame. Looking in the directionof displacement of the piston the drive shaft acts upon the guidehousing approximately in the center of the latter. If a windshield wipersystem is fitted in a motor vehicle in such a way that the drive shaftis arranged closely to the lower rim of the windshield, the fronthousing portion moves in front of the pane, whereas the rear housingportion moves in pendulum fashion in the engine compartment. It isthereby of advantage that only about half of the guide housing ispositioned in front of the pane to be cleaned and, as a matter of fact,the view through the windshield is only impeded in exceptional cases. Itis however a disadvantage that the other half of the housing dipsrelatively deep into the engine compartment, so that sufficient spacehas to be created there. However this space is not available in allvehicle models.

The guide housing of the known embodiment is constructed to besubstantially symmetrical to the direction of displacement of thepiston, which thus is displaceably guided in the center of the saidguide housing and intersects the axis of rotation of the guide housing.The wiper arm-and-blade assembly is centrically fixed to the free end ofthe piston, with the wiper blade adjusted extactly in the longitudinaldirection of the piston. The wiper blade ends at a spacing from the freeend of the piston, so that between the axis of rotation of the guidehousing and the adjacent end of the wiper blade there is left arelatively large area which is not wiped. This substantially symmetricalshape of the guide housing and the wiper arm-and-blade assembly can forsome vehicles mean that the wiper blade projects relatively far into thewindshield to be cleaned even in its parking position which fact is notaccepted by some vehicle manufacturers predominantly on grounds ofstyle.

On the whole it has to be stated that the known version cannot be usedfor all vehicle models.

Thus the object of the invention is to develop a windshield wiper systemof this kind in such a way that it can also be used when there is onlylittle space available for mounting purposes in the engine compartment.The wiping area is of course expected to meet the present standard or iseven to be enlarged, if possible.

This problem is solved according to the invention with thecharacterizing features of claim 1.

The present invention is thereby based on the idea of being able to makethe volume of the guide housing rear portion considerably smaller, whenthe shaft from which the direction of displacement of the piston isderived is arranged between the axis of rotation of the guide housingand the front end of the guide housing. Normally this measure makes thefront portion of the housing larger, however its rear portion is so muchdiminished that it can be fitted in a motor vehicle even if there arenarrow space conditions.

It is true that a wiper system has been known from the DE-AS No. 1 066890 in which the windshield wiper is also radially retracted andextracted during the swivelling motion with the radial direction ofdisplacement being derived from the rotation of a shaft which, lookingin the longitudinal direction of the windshield wiper is arranged infront of a toothed segment. However the pinion fixed on this shaft doesnot mesh with a stationary toothed segment as in the subject matter ofthe present invention. Moreover this shaft or the pinion is co-axiallyarranged to the axis of rotation of the entire system, whereas in thepresent invention the shaft is arranged with a spacing from the axis ofrotation in the space between this axis of rotation of the guide housingand the front and of the guide housing.

In contrast to the embodiment initially mentioned the drive shaft nowacts upon the guide housing outside the center of the latter closely tothe rear rim. Thus the front portion of the housing projects relativelyfar into the pane to be cleaned, so that the view conditions could beaffected. In order to eliminate this disadvantage according to anotherfeature of the invention the piston is guided laterally spaced from theaxis of rotation of the guide housing. This proposal is based on theidea of being able to differ the known symmetric shape of the housing,when the piston is not centrally guided. The rim of the guide housingadjacent to the piston of a preferred embodiment extends with a smallspacing from the piston and preferably linearly parallel to it. Thus inthe parking position this rim of the guide housing adjecent to thepiston does only project into the windshield area slightly farther thanthe windshield wiper, because compared with the known embodiment thespacing between the said housing rim and the windshield wiper looking inthe direction of wiping can be reduced. In this connection it is thuspointed out that independent protection is claimed for this idea becauseit solves space problems independently of the embodiment according toclaim 1 and improves the view conditions, because in comparison with theprior art the rim of the guide housing closely arranged to thewindshield wiper projects only insignificantly into the area of thewindshield in the parking position and in the reversing position of thewiper blade the guide housing projects only slightly into the enginecompartment by means of this rim.

In reciprocating wiper system known until now--as has beenmentioned--the wiper blade has been arranged on the longitudinal axis ofsymmetry of the piston. In an arrangement like this the wiper blade endsin front of the piston compulsorily, so that in the reciprocating wipersystem according to the invention this would result in a relativelylarge unwiped area between the axis of rotation of the windshield wiperand this end of the wiper blade. In order to eliminate this disadvantagethe wiper arm-and-blade assembly or the wiper blade respectively is notarranged symmetrically and the wiper arm of the wiper arm-and-bladeassembly is in its end area bent in such a way that the wiper blade isarranged laterally beside the wiper arm. By this measure the wiper bladecan be lengthened in comparison to known embodiments, so that it ends inan area laterally beside the guide housing. The wiper blade of apreferred embodiment is lengthened as far as to the vicinity of the axisof rotation. A solution of this kind is of advantage, if the drive shaftfor the guide housing is inserted in an aperture of the windshield to becleaned. Independent protection is claimed for this embodiment too,because this idea can of course bring about an improved view inconventional reciprocating wiper systems.

The invention and its advantageous embodiments are described below indetail by way of the embodiments shown in the drawing, in which

FIG. 1 is a longitudinal section through the guide housing of a wipersystem.

FIG. 2 is a view in the direction of arrow P,

FIG. 3 is a section taken on the line III--III,

FIG. 4 is a section taken on the line IV--IV,

FIG. 5 shows the mounting of a guide housing of this kind in a motorvehicle,

FIG. 6 is a skeleton view of another embodiment of a wiper system,

FIG. 7 shows a third embodiment and

FIG. 8 is a section taken on the line VIII--VIII.

In FIG. 1 a guide housing is designated 10, which includes adimensionally stable base plate 11 and a plastics covering cap 12. Tothe base plate 11 two bearings 13 and 14 are fixed with a spacing fromeach other, in which bearings is guided a linearly displaceable piston15. To the front end of this piston 15 can be fixed in a known mannerthe fastening member of a wiper arm. A drive shaft 16 is fixed in amanner protected against rotation on the base plate 11, which driveshaft is rotatably movable in bearings of a bearing bush 17. Upon thefree end of the said drive shaft 16 acts in a known manner a crosssteering mechanism which has not been shown in detail in FIG. 1. Thusthe drive shaft 16 and the guide housing as well are driven in pendulumfashion about the axis of rotation 16.

The linear displacement of the piston 15 is derived via a crankmechanism from the rotation of a shaft 20 rotatably mounted on the guidehousing 10, which shaft carries a pinion 21 outside the guide housingwhich pinion meshes with the stationarily arranged toothed segment 22. Acrank 23 is torsionally firm fitted on this shaft 20. On the said crankis articulated a push rod 24, whose other end acts upon the piston 15between the two bearings 13 and 14.

Especially from FIG. 1 can be seen that the said crank shaft 20 isarranged between the axis of rotation A of the guide housing 10 and thefront end of the guide housing 10 carrying the bearing 13. On the otherhand this results in a smaller rear portion of the guide housing incomparison with known embodiments and the drive shaft 16 now acts uponthe guide housing closely to its rear end and not for example centrallyon the guide housing. FIG. 5 indicates the mounting of a wiper system ofthis kind in a motor vehicle. The pane to be cleaned is designated 30and the hood 31. It can be seen from the representation of FIG. 5 thatto the left of the axis of rotation A only a relatively small mountingspace is required. On the other hand it can also be seen from FIG. 5that the front portion of the guide housing 10 projects relatively farinto the area of the windshield 30 to be cleaned, which fact is ofimportance for the developments described below.

Due to an arrangement of shaft 20 and pinion 21 according to theinvention it is now possible to form the stationary toothed segment 22as a circular ring with internal teeth. Compared with known embodimentshaving only a semi-circular toothed segment this embodiment has theadvantage of a greater stability and accuracy which fact has afavourable effect on the running properties and in particular on thenoise behaviour. This toothed segment 22 is integrally worked into thegenerated surface 35 of a substantially cup-shaped supporting frame 36,onto which the bearing bush 17 is also integrally formed. This one-piececonstruction of bearing bush 17 and toothed segment 22 provides aquieter running in comparison with known systems in which the toothedsegment is fixed onto the supporting frame as an independent part. Inaddition these measures are cost-saving.

In the interest of guiding the piston 15 free from play the two bearings13 and 14 are secured in a dimensionally firm way to the same part,namely to the base plate 11. The rear bearing 14 which is positionedclosely to the axis of rotation A of the guide housing 10 is therebyformed on a pillow block 40 having two shanks 41 and 42 running towardseach other in the shape of a V. The ends of these shanks are screwedonto the base plate 11. The bearing 14 is located at the transitionbetween the two shanks 41 and 42, thus approximately in the center ofthe pillow block 40. The pillow block 40 extends at least in this areawith a spacing from the base plate 11, so that there is some space leftfor the push rod 24 through-projecting underneath the said bearing 14.

To the rear end of the piston 15 is fixed a radially protrudingextension arm 45 in a torsionally firm way whose free end is guided in aguide rail 46 in order to protect the piston 15 against rotation. As inparticular FIG. 2 shows this extension arm is bent in such a way thatthe conceived connecting line VI between the rear end of the piston 15and the guide area on the guide rail 46 is adjusted approximately inparallel to the shank 41 of the pillow block 40. Looking in thedirection of displacement of the piston 15 the guide area betweenextension arm 45 and guide rail 46 is thus positioned before the rearend of the piston which fact permitted to reduce the size of the guidehousing rear portion. By the appropriately slantingly arranged shank ofthe pillow block 40 it is thereby achieved that the adjusting stroke ofthe piston and thus the extension arm 45 is not reduced. Just as the twobearings 13 and 14 the guide rail 46 is fixed onto the base plate of theguide housing 10 thus enabling an accurate adjustment of all these guideelements relative to one another.

FIG. 6 shows another embodiment of the invention with the shaft carryingthe pinion 21 once again arranged between the axis of rotation A of theguide housing 10. In this embodiment it is important, that the piston 15does not intersect the axis of rotation A of the guide housing 10, butis guided laterally to it with a spacing in a set-off way. The rim 40 ofthe guide housing 10 adjacent to the said piston 15 can then be linearlyformed and be arranged with a small spacing from the said piston. Thisis possible, because so-to-speak the drive mechanism for the said piston15 is not arranged symmetrically, but moved to one side of the piston.One can see from FIG. 6 that between the two bearings 13 and 14 anextension arm 45 projects radially from the piston 15, which extensionarm itself is guided in a guide rail 46. In contrast to the embodimentaccording to FIGS. 1 to 5 the push rod now acts upon the extension arm45 and not directly upon the piston 15. FIG. 6 thereby shows anembodiment in which the said extension arm 45 is guided on the guiderail between the point of articulation of the push rod 24 and the piston15, whereas in the embodiment according to FIG. 7 the push rod 24 iscentrally articulated between piston 15 and guide rail 46 on the saidextension arm 45. In this embodiment according to FIG. 7 the push rod 24is arc-shaped, that means, seen in general, it has a bulge between itstwo points of articulation, which bulge points away from the piston 15,in order to provide free motion tolerance for the said push rod 24without the risk of colliding with the bearing 14.

From FIGS. 6 and 7 can furthermore be seen that the shaft 20 and theaxis of rotation A of the guide housing 10 are positioned on a straightline G, which is adjusted at an angle to the direction of displacementof the piston 15. This measure also contributes to a satisfactory freemotion for the push rod 24 and the guide housing can nevertheless beformed in a space-saving manner.

Thus on the whole it has to be stated that by moving the shaft 20 and/orthe piston 15 and together with them the point of articulation of thepush rod 24 in comparison with known embodiments a space-saving guidehousing 10 is created which can be also used when there are narrow spaceconditions in particular motor vehicle models and the view through thewindshield is nevertheless only slightly impeded.

In FIGS. 6 and 7 the wiper arm-and-blade assembly 50 of the windshieldwiper system is also shown. Part of this wiper arm-and-blade assemblyare a wiper arm 51 with a wiper rod 52 and a wiper blade 53. The frontend portion of the wiper rod is bent in such a way that the wiper blade53 is laterally arranged beside the wiper arm 51. This construction ofthe wiper arm-and-blade assembly 50 is known in itself has however untilnow not yet been used in so-called reciprocating wiper systems. Due tothis construction of the wiper arm-and-blade assembly the wiper blade ofa reciprocating wiper system can be longer than in known embodiments, sothat it ends in an area laterally beside the guide housing 10. FIG. 7shows an embodiment in which this wiper blade 53 ends approximately inthe center between the axis of rotation A and the rear bearing 14. Inthe embodiment according to FIG. 6 the wiper blade ends closely to aplane E through the axis of rotation A of the guide housing 10perpendicularly conceived to the direction of displacement of the piston15. The wiper blade 53 of this embodiment according to FIG. 6 thus endsas closely adjacent to the axis of rotation A of the guide housing 10 aspossible, by which measure the wiping area can be enlarged in comparisonwith known embodiments.

Whereas thus in the embodiment according to FIGS. 1 to 5 the guidehousing--as it is known in itself--is formed so-to-speak symmetricallyto the longitudinal axis of the piston, the guide housings according toFIGS. 6 and 7 are unsymmetrical in such a way that the wiper blade isguided closely to the piston 15 and in particular also extends closelyto the axis of rotation A. This unsymmetrical construction of the guidehousing 10 does not require a larger space. In some motor vehicle modelsa windshield wiper system of this kind can even be better accommodated.

We claim:
 1. A windshield wiper system for a motor vehicle comprising:aguide housing having a front end; drive means for driving said guidehousing in a pendulum fashion about an axis; a piston having two opposedends, said piston being linearly displaceable in said guide housingalong a longitudinal path which is laterally spaced from the axis ofrotation of said guide housing; a wiper arm and blade assembly attachedto said piston for movement therewith; and means for linearly displacingsaid piston in said housing along said longitudinal path, said means forlinearly displacing said piston includes:a shaft having upper and lowerends rotatably mounted on said guide housing; a crank coupled to theupper end of said shaft; a push rod having two opposed ends, one of saidends of said push rod being coupled to said crank and said other end ofsaid push rod being coupled to said piston; a pinion coupled to saidlower end of said shaft, and a stationary toothed segment mountedoutside of said guide housing and meshing with said pinion.
 2. Awindshield wiper system according to claim 1, wherein said guide housingincludes a rim which extends along a path which is parallel to andlaterally spaced from said piston.
 3. A windshield wiper systemaccording to claim 1, wherein said means for linearly displacing saidpiston further includes an extension arm coupling said other end of saidpush rod to said piston, said guide housing further including two spacedapart bearings and a guide rail for guiding said piston and saidextension arm, respectively.
 4. A windshield wiper system according toclaim 3, wherein said other end of said push rod is pivotally mounted tosaid extension arm.
 5. A windshield wiper system according to claim 4,wherein said push rod is mounted to said extension arm at a locationwhich is between said piston and said guide rail.
 6. A windshield wipersystem according to claim 4, wherein said extension arm has a first andsecond end, with said first end being coupled to said push rod andwherein said guide rail for said extension arm is located between saidfirst and second ends.
 7. A windshield wiper system according to claim4, wherein said push rod is pivotally mounted to said crank, and saidpush rod is shaped to form a bulge which points in a direction away fromsaid piston.
 8. A windshield wiper system according to claim 7, whereinsaid push rod is arc-shaped.
 9. A windshield wiper system according toclaim 1, wherein said shaft and said axis of rotation of the guidehousing are positioned on a straight line which is at an angle to thedirection of displacement of the piston.
 10. A windshield wiper systemaccording to claim 1, wherein said wiper arm and blade assembly includea wiper arm and wiper blade, wherein said wiper arm is bent in such away that said wiper blade is arranged laterally beside said wiper arm.11. A windshield wiper system according to claim 10, wherein said wiperblade ends in an area laterally beside said wiper arm.
 12. A windshieldwiper system according to claim 10, where said wiper blade ends closelyto an imaginary plane which extends through said axis of rotation of theguide housing and is perpendicular to the direction of displacement ofthe piston.
 13. A windshield wiper system according to claim 10, whereinsaid rim of the guide housing extends parallel to the wiper blade in thearea adjacent to said wiper blade.